Iris recognition is a method of biometric authentication that uses pattern recognition techniques based on high-resolution images of the irises of an individual's eyes. Iris recognition uses camera technology, typically employing near infrared (NIR) illumination to see through the iris coloration, to create images of the detail-rich, intricate structures of the iris. Converted into digital templates, these images provide mathematical representations of the iris that yield unambiguous positive identification of an individual.
One problem with iris recognition is that focusing is extremely difficult when accurately capturing near infrared (NIR) iris images. To get iris features with dark eyes NIR illumination and sensors are used. Due to the NIR the sensor is not as efficient compared to visible so there needs to be more illumination. Even with intense illumination the camera aperture setting is often such that the depth of field is short, which is a major factor in capturing images that are not in focus. Autofocusing does not work because the iris can be located anywhere within the operating range of the iris camera and because the camera lens has a very small depth of field.